The present disclosure relates to a coupling mechanism and a sheet feed device and an image forming apparatus that include such a coupling mechanism, and particularly relates to a coupling mechanism that includes a drive transmission member to which a driven member is fixed and a coupling member which is engaged with the drive transmission member and a sheet feed device and an image forming apparatus that include such a coupling mechanism
A paper feed cassette (sheet storage cassette) is used as a cassette for feeding cut paper or the like in an image forming apparatus such as a copying machine or a printer. In the paper feed cassette, a large number of sheets before printing are previously stocked, and a paper feed roller, a pickup roller and the like provided in the vicinity of the paper feed cassette are used to separate and supply the sheets one by one from the uppermost layer of a bundle of sheets stacked within the paper feed cassette.
There is a paper feed cassette that includes a sheet loading plate in which sheets are placed on its upper surface. In the sheet loading plate, an upstream end in a paper feed direction is supported to the inside of the bottom surface of the paper feed cassette, and the sheet loading plate can be rotated about the support point with a downstream end portion in the paper feed direction serving as a rotation end (free end). In the paper feed cassette, an actuation plate which makes contact with the sheet loading plate from below so as to raise and lower the rotation end of the sheet loading plate and a drive transmission member to which the actuation plate is fixed are provided. In the main body of the apparatus, a coupling member is provided which is engaged with the drive transmission member so as to transmit a rotation drive force to the drive transmission member.
For example, the drive transmission member is formed with a shaft portion to which the actuation plate is fixed and an engagement pin which is fixed to the end portion of the shaft portion on the side opposite to the actuation plate and which is extended in a direction intersecting the shaft portion. On the coupling member, a plurality of engagement protrusions are provided which are protruded in the axial direction of the shaft portion and which are engaged with the engagement pin. In a state where the engagement pin is inserted between the engagement protrusions, the coupling member is positively rotated, and thus the engagement pin is pressed by the pressing surface of the engagement protrusion in the positive rotation direction, with the result that the drive transmission member is positively rotated. In this way, the actuation plate is rotated so as to stand up, and thus the sheet loading plate is raised.